Objective: To determine, on the basis of iodide uptake inhibition (IUI), whether associations between urinary concentrations of IUI agents (perchlorate, nitrate, and thiocyanate), as total perchlorate equivalent concentration (PEC), and serum thyroid parameters suggest functional thyroid abnormalities. Additional thyroid hormone measures were released to augment the National Health and Examination Survey (NHANES) 2001 to 2002 data set, which we used in this study.
Methods: Enhanced thyroid hormone measures released to augment the National Health and Examination Survey (NHANES) 2001–2002 data set were used in this study. Multiple regression was used to assess the relationships among total thyroxine (TT4), free thyroxine, total triiodothyronine (TT3), free triiodothyronine, and thyroid- stimulating hormone (TSH) and PEC.
Results: PEC was weakly and negatively associated with TT4, but not with TSH, TT3, or free hormone. This association with TT4 appears to be dominated by nitrate and thiocyanate.
Conclusion: No evidence of functional thyroid abnormality (eg., low thyroid hormone coupled with high TSH) was seen with exposure to the combined IUI agents and enhanced estimates of thyroid function.
From Intertox, Inc. (Ms Bruce and Drs Corey and Pleus), Seattle, Wash; and Division of Environmental Health Sciences, School of Public Health, University of Minnesota (Dr Mandel), Minneapolis, Minn.
Address correspondence to: Richard C. Pleus, PhD, Intertox, Inc, 600 Stewart St., Suite 1101, Seattle, WA 98101 (firstname.lastname@example.org).
Funding for this study was provided by the Perchlorate Study Group (PSG), a consortium of manufacturers and users of perchlorate. The PSG member companies include Aerojet General Corporation, American Pacific Corporation, Alliance Techsystems, Inc., and Lockheed Martin Corporation. Neither the PSG nor any of its member companies had any role in the conduct of the study or in the writing or editing of the article.
Intertox is a health science research firm and has conducted work for the PSG and other users and/or manufacturers of perchlorate. Dr. Pleus has served as an independent expert and has provided expert testimony on the toxicology of perchlorate. Dr. Mandel has done general consulting for Lockheed Martin, unrelated to this topic.
The authors declare no conflict of interest.